Propagation Constant Measurement Based on a Single Transmission Line Standard Using a Two-Port VNA.

This study presents a new method for measuring the propagation constant of transmission lines using a single line standard and without prior calibration of a two-port vector network analyzer (VNA). The method provides accurate results by emulating multiple line standards of the multiline calibration method. Each line standard was realized by sweeping an unknown network along a transmission line. The network need not be symmetric or reciprocal, but must exhibit both transmission and reflection. We performed measurements using a slab coaxial airline and repeated the measurements on three different VNAs. The measured propagation constant of the slab coaxial airline from all VNAs was nearly identical. By avoiding disconnecting or moving the cables, the proposed method eliminates errors related to the repeatability of connectors, resulting in improved broadband traceability to SI units.

Effects of Incretin Pathway Elements on Bone Properties.

Introduction The effects of incretin-based drugs, such as receptor agonists of glucagon-like peptide-1 and inhibitors of dipeptidyl peptidase-4, on bone metabolism are not completely clear yet. The aim of this study is to compare the effects of glucagon-like peptide-1 and inhibitors of dipeptidyl peptidase-4 on the bone to see how different elements of the incretin pathway affect bone quality in terms of biomechanical properties, bone turnover, and mineral properties. Materials and methods Forty 10-week-old Wistar rats were divided into four groups: a control group, a control diabetic group, a diabetic group treated with sitagliptin, and a diabetic group treated with exenatide. Type 2 diabetes was simulated by dietary manipulation in addition to low-dose streptozotocin, and then two different incretin-based drugs were administered. The rats were sacrificed after five weeks of therapeutic treatment. Their serum was analyzed with the enzyme-linked immunosorbent assay (ELISA) method for basic bone turnover markers, and their right femur was subjected to a three-point bending test. Finally, Hematoxylin & Eosin staining, in addition to Raman spectroscopy, were employed to access the collagen and mineral properties of the bone. Results Both incretin-based drugs reduced osteoclast function; however, they were not able to restore osteoblastic function to normal. The net effect on bone strength was surprising: bone elasticity was restored by the antidiabetic treatment, but bone strength deteriorated. Exenatide had a slightly more pronounced effect, which, although not significant, points to the direction that dipeptidyl peptidase-4 (DPP4) may be a linking factor between reduced osteoclastic function and reduced bone formation, as suggested by the literature. Conclusion DPP4 receptors seem to be one of the links between reduced osteoclast function and reduced bone remodeling, so DPP4 inhibition can be more detrimental to the bone than glucagon-like peptide-1 (GLP-1) receptor agonists.

Carpometacarpal Dislocation of the Third to Fifth Fingers and an Associated Fracture of the Hamate in a Military Paratrooper.

Multiple carpometacarpal dislocations with a simultaneous fracture of the hamate represent less than 1% of all injuries to the hand and wrist regions, with a scarcity of published cases. These injuries usually require a great force, and diagnosis can be missed or delayed because of the high likelihood of other severe concomitant injuries. We report a case of acute closed dislocation of the third through fifth carpometacarpal joints and an associated fracture of the hamate in a military paratrooper. The injury was caused by a wrong landing technique during parachuting. The patient was managed with primary surgical repair, and after a six-month follow-up, he has excellent functional results. The fact that both this clinical entity and the mechanism of injury are very unusual a high index of suspicion is needed, especially for orthopedic surgeons working in military hospitals. Additionally, given that there is a paucity of published cases and optional treatment is controversial, this study corroborates the superiority of surgical repair in a long-term basis.

A Miniaturized UHF-Band Rectenna for Power Transmission to Deep-Body Implantable Devices.

This paper presents the design, simulation, and fabrication of a 50 Ohm miniaturized rectenna for wireless energy harvesting for leadless pacemakers. The paper evaluates the performance of each section separately and also while cascaded. The system is designed to work at ultra-low RF input power. When the rectenna is placed 5 cm away from the body surface in simulations, the amount of received power is approximately -20 dBm. The proposed antenna is a miniature spiral PIFA with circular polarization at 673 MHz. The measured results, in and outside sheep's fat tissue, show that about 15 MHz bandwidth can be realized with [Formula: see text] below -10 dB and an axial ratio below 3 dB. Two types of rectifiers are fabricated and compared to choose the best one for such a system. Then, unlike most other researches which selected the doubler rectifier structure, this paper uses a single-diode rectifier structure at this power level. The rectenna can be encapsulated in a cylinder with a radius of 5 mm and a height of 3.2 mm. The efficiency of the rectenna reaches 40% at -20 dBm input power.